Windage troubles at long range

I am having problems with my 7mm STW shooting 6 inches right at long ranges. Ive shot it at 400, 500,600,700 yards and it keeps shooting the same 6 right. Ive shot it again at 100 and 200 and 300 and it is right on the money. im shooting 180 berger VLD bullets at 2914fps. The gun is shooting really good groups out there just six inches right and on calm days. Scope is a markV 8.5-25 leupold, sitting on a krieger barrel and pre64 model 70 Winchester action. any help would be apprciated.

Thats an interesting problem. Did it just start doing this? It is strange that your impact is the same 6" right at each distance from 400-700, and good to 300. If the groups are tight it is possibly a scope issue, but if it was the Reticle not being perpendicular to the bore the deviation would vary with range. So would a bedding or scope mount issue. Might be a parallax issue. How old is your MK 4? A few years back Leupold had some parallax adjstment problems with the 8.5x25's. You might try a different scope on the rifle to see if the problem persists.

That is my thought, that scope is canted. Have you tracked dial up or hold @ 100 on a plumbline, do you use a level for consistency .Plumb a line at 100 and dial up 20 moa and see that it is still in line. Does it shoot 6'' at all yardages or progressive worse as range increases .Or it doesnt track plumb.